A Rude Awakening

With such mild temperatures, some trees here in the north woods are experiencing early leaf out. All around the Wolf Ridge property, we continue to see the opening of buds when the temperatures rise.

February 12

Tree buds are grown at the end of the summer using excess sugars, and then go dormant until spring time rolls around. During winter dormancy, trees slow everything down including cell growth, metabolism, and energy consumption. If temperatures warm, the buds can begin to open, exposing flowering parts and tender young leaves to any following freezing periods. This is unlikely to kill a tree but it does use energy the would have been used in the spring leaf out. Once that energy is used up, it can set a tree’s blooming period back tremendously. Which means, a tree that commonly blooms in early spring may not even show signs of leafing out until the end of the season. Some trees that we have been seeing undergoing this phenomenon are Tamaracks, Red Maples and Balsam Poplars.

February 25

Science in the Solarium!

Being curious people, we decided to do a science experiment to see what we and learn about how climate affects bud burst. We know that warm temperatures start the early opening of flower and leaf buds. Do all kinds of trees respond the same? How long does it take for each tree to show a bud burst, experience first leafing, and finally flower, when exposed to warm temperatures.

At the south end of Wolf Ridge’s Education Building there is a sunny solarium – the perfect place to create a “false spring.” Each Tuesday morning we head outside to collect foot-long Balsam Poplar, Tamarack, and Red Maple twigs. We put each week’s twigs in water in a bucket labeled with the date it was collected. Then we check them to see if there are changes.

On February 3rd we came into the solarium to find the Balsam Poplar that was cut on January 12th had its first leaves showing! By February 25, all three tree species buds had burst open: Leaves on the balsam poplar, needles on the tamarack, and flowers on the red maple. They all opened at different times. Why was that? Hopefully this and additional experiments will shed light on how warmer winter temperatures could affect our trees here in Northern Minnesota. As we can see from this Balsam Poplar branch, if the temperatures are right, leaves could grow in January and February, but what might happen if the warm weather is followed by a big freeze?

We will continue to cut branches and monitor growth throughout the spring, so we may begin to answer the question of what warmer temperatures could do to our trees! Stop by the solarium on your next visit to Wolf Ridge and you will find this living science experiment taking place before your very eyes!